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Eye Tracker Device

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martinkonopka edited this page Mar 6, 2019 · 7 revisions

Code: ET

Eye tracker device in UXC provides control of Tobii Pro remote eye trackers. It uses Tobii Pro SDK NuGet packages for communicating with the Tracker. Tobii Pro TX300 and X2-60 devices were tested.

Simulator

If no eye tracker is available, you can simulate gaze positions with mouse cursor. Switch the Eye Tracker device setting in UXC options to the Simulator and reconnect the device.

UXC app options with eye tracker selection

Configuration

  • App configuration - section [Devices.EyeTracker]
    • SelectedDriver = Tobii Pro or Simulator - specifies which driver to use for eye tracker device.
[Devices.EyeTracker]
SelectedDriver = Tobii Pro

Recording setup

Before recording, the eye tracker should be calibrated for participant. Use Stimuli timeline steps specific to eye tracker for calibration and validation, if eye tracker is used in your recording.

Recording data

Recording data contains raw gaze data returned by the tracker in GazeData objects. Structure of the GazeData objects reflects original Tobii Pro gaze data structures.

For reference, see GazeData class definition in the project's repository.

GazeData

Data structure containing raw gaze data from eye tracker.

  • Timestamp : DateTime - local timestamp when the data was received from the eye tracker.
  • TrackerTicks : long number - Eye tracker timestamp ticks of the current sample.
  • Validity : GazeDataValidity - validity code of the eyes tracked by the tracker.
  • LeftEye : EyeGazeData - gaze data for the left eye.
  • RightEye : EyeGazeData - gaze data for the right eye.

EyeGazeData

Data structure describing one eye in GazeData object.

  • Validity : EyeGazeDataValidity - validity of this eye.
  • GazePoint2D : Point2D - normalized 2D coordinates of the gaze on the screen.
  • GazePoint3D : Point3D - eye gaze point on the calibration plane given in millimeters (User Coordinate System, see Tobii Pro docs - Coordinate system).
  • EyePosition3D : Point3D - position of the eye in 3D space given in User Coordinate System.
  • EyePosition3DRelative: Point3D - position of the eye in 3D space relative to the track box given in the Track Box Coordinate System (see Tobii Pro docs - Coordinate system).
  • PupilDiameter : double - estimated diameter of the eye pupil in millimeters (see Tobii Pro docs - Pupil diameter).

GazeDataValidity

Enumerated value of valid eyes tracked by the eye tracker, see Tobii Pro docs - Validity codes. Only samples with value of Both, Left or Right should be used for data analysis. All possible values:

  • None
  • Both
  • Left
  • Right
  • ProbablyLeft
  • UnknownWhichOne
  • ProbablyRight

EyeGazeDataValidity

Enumerated value of single eye data validity. Only samples with value of Valid should be used for data analysis. GazeDataValidity value is combination of these validity codes for both eyes. All possible values:

  • Invalid
  • Valid
  • Probably
  • Unknown

Recording log

Eye tracker device logs following data during the recording. This log can be found in the session recording data in ET_log.json file.

  • Connection status.
  • Device details - device name, family, product ID.
  • Track box coordinates
  • Display area coordinates
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